SufficientlyAdvanced
1 µW
- Joined
- Feb 4, 2016
- Messages
- 2
Hey Everyone,
I'm a noob when it comes to high power brushless stuff, so forgive me if this isn't an appropriate board for this question. I've got a project where the math works out, but I don't have any hands-on experience and was hoping to get some opinions.
Rather than pulling a glider, I'd like to make a winch that can pull me straight up 20-30 feet. I'd like to keep it as small and cheap as possible, and there seems to be a pretty steep price difference between a 6S ESC and a 12S ESC, so:
-A 240 Kv motor like this one http://www.hobbyking.com/hobbyking/...0_High_Voltage_Brushless_Outrunner_240KV.html
has a Kt of (240/(60/2pi))^-1 = 0.0398. At 22 Volts that gives a motor speed of 552.92 rad/s
-With a 12:90 tooth belt from motor to reel, the reel speed will be 552.92/7.5 = 73.72 rad/s. Assuming the reel diameter is 1/2" (0.00635m radius) that becomes a line speed of ~0.47 m/s, so ascending about 1.5 feet per second top speed.
-Assuming 100kg of weight being pulled up, with 1 m/s^2 acceleration, that requires 1081 N, or 6.86 Nm of torque from the reel. Knowing that T = I * Kt * gear ratio that comes out to 22.9 amps of current draw. The rope is a 1/8" diameter nylon paracord, and as that wraps around the reel, the reel diameter is going to effectively increase. That hopefully tops out at a reel diameter of 1", or .0127m radius. At that point the torque required will be doubled, so 13.72 = I * 0.0389 * 7.5, so I then = 47.03 amps.
This seems manageable number wise, well within the motor specs, a 6S 100 amp ESC and a 22.2 3000 mAh LiPo with 35C ought to be able to handle the NUMBERS. I have a BS in Electrical Engineering, but I've never so much as held a brushless outrunner before, so I have no idea if this makes PHYSICAL sense.
TL;DR In your opinion, does a 240 Kv motor on 6S with a 1:7.5 gear reduction have enough oomph to reel 200lbs straight up at 1.5 feet/sec? What would you recommend otherwise?
I'm a noob when it comes to high power brushless stuff, so forgive me if this isn't an appropriate board for this question. I've got a project where the math works out, but I don't have any hands-on experience and was hoping to get some opinions.
Rather than pulling a glider, I'd like to make a winch that can pull me straight up 20-30 feet. I'd like to keep it as small and cheap as possible, and there seems to be a pretty steep price difference between a 6S ESC and a 12S ESC, so:
-A 240 Kv motor like this one http://www.hobbyking.com/hobbyking/...0_High_Voltage_Brushless_Outrunner_240KV.html
has a Kt of (240/(60/2pi))^-1 = 0.0398. At 22 Volts that gives a motor speed of 552.92 rad/s
-With a 12:90 tooth belt from motor to reel, the reel speed will be 552.92/7.5 = 73.72 rad/s. Assuming the reel diameter is 1/2" (0.00635m radius) that becomes a line speed of ~0.47 m/s, so ascending about 1.5 feet per second top speed.
-Assuming 100kg of weight being pulled up, with 1 m/s^2 acceleration, that requires 1081 N, or 6.86 Nm of torque from the reel. Knowing that T = I * Kt * gear ratio that comes out to 22.9 amps of current draw. The rope is a 1/8" diameter nylon paracord, and as that wraps around the reel, the reel diameter is going to effectively increase. That hopefully tops out at a reel diameter of 1", or .0127m radius. At that point the torque required will be doubled, so 13.72 = I * 0.0389 * 7.5, so I then = 47.03 amps.
This seems manageable number wise, well within the motor specs, a 6S 100 amp ESC and a 22.2 3000 mAh LiPo with 35C ought to be able to handle the NUMBERS. I have a BS in Electrical Engineering, but I've never so much as held a brushless outrunner before, so I have no idea if this makes PHYSICAL sense.
TL;DR In your opinion, does a 240 Kv motor on 6S with a 1:7.5 gear reduction have enough oomph to reel 200lbs straight up at 1.5 feet/sec? What would you recommend otherwise?